The present disclosure relates generally to reducing emissions from power plant exhaust and, more specifically, to systems and methods of reducing emissions by recovering carbon dioxide from a gas stream.
Power generating processes that are based on combustion of carbon-containing fuel produce carbon dioxide as a byproduct. Typically, the carbon dioxide is one component of a mixture of gases that results from or passes unchanged through the combustion process. It may be desirable to capture or otherwise remove the carbon dioxide and other components of the gas mixture to prevent the release of the carbon dioxide and other components into the environment.
At least one known method for removing carbon dioxide from gas streams includes an absorptive/stripping-type regenerative process using aqueous monoethanolamine (MEA) or hindered amines like methyldiethanolamine (MDEA) and 2-amino-2-methyl-1-propanol (AMP). However, the process can sometimes result in sharp increases in the viscosity of the liquid absorbent, which can decrease the mass transfer of carbon dioxide into the absorbent. Moreover, energy consumption in the MEA process can be quite high, due in large part to the need for non-absorbing co-solvent (e.g., water) heating and evaporation. Furthermore, MEA-based absorption systems may not have the long-term thermal stability, in the presence of oxygen, in environments where regeneration temperatures typically reach at least about 120° C.